The invention relates broadly to an agricultural harvesting machine with a measurement device for investigating a crop flow that includes an optical detection unit for detecting light reflected by the crop and an evaluation unit that evaluates the spectrum of the detected light in order to derive properties of the crop (13) therefrom.
As is known, agricultural harvesting machines convey and process crop and, for many and various reasons, it is interesting to investigate crop conveyed through the machine during a harvesting operation with respect to the properties thereof, such as moisture and/or content of starch/sugar, proteins, crude fiber, oil, minerals, raw ash, etc.
A crop flow can be investigated in a manner known per se using a measurement device that operates on the basis of near infrared (NIR) spectroscopy. Measurement devices known from the prior art therefore comprise an optical detection unit disposed at the crop flow, which detects light reflected by the crop (which is irradiated with a light source). An evaluation unit signal-connected thereto and comprising a radiation detector analyzes the spectrum of the detected light in order to derive properties of the crop therefrom.
Measurement devices that operate in this manner, such as those available on the market for self-propelled forage harvesters, are designed as a compact assembly enclosed in a housing and are advantageously placed in the direct vicinity of the crop flow. For forage harvesters, the outer wall of the transfer device (also referred to as the “upper discharge chute”) is typically used as the installation site for the housing of the measurement device. For example, EP 1 570 723 B1 describes a bracket system for a measurement device operating with near infrared spectroscopy, said bracket system being installable on the transfer device of a forage harvester.
The design described in EP 1 570 723 B1, however, has several disadvantages. For example, the sensors required for detection of the infrared light are exposed to strong vibrations and accelerations during operation, which are caused by crop flowing past and/or by operation-induced machine vibrations and accelerations that are transferred to the transfer device. During travel across uneven terrain in particular, vibrations have a particularly strong effect on the transfer device due to the lever effect (with increasing distance from the machine) and, in the extreme case, can be audibly perceived as impacts. The stability of the sensitive sensors is therefore limited. Also, considerable installation space is required to house the sensors, which can be provided on the outer wall of the transfer device only with the compromise of non-optimal positioning. Additionally, the design of the measurement device increases the risk of theft since the measurement device is attractive to thieves due to the high value and easy removability thereof.